The present invention relates generally to an in-vehicle device, and more specifically, to a method and apparatus of detecting abnormal driving condition.
Currently, traffic accidents such as vehicle rear-end collisions often occur, with rear-end collisions making up a large proportion of all traffic accidents. Anti-collision systems in current vehicles can be divided into two types: (1) radar or sonar based probing devices, and (2) communication network based anti-collision systems. A radar or sonar principal based probing apparatus transmits light, electromagnetic or ultrasonic waves toward a certain direction. These waves then reflect when they encounter an obstacle, wherein the reflected waves may be detected by the probing apparatus. The distance of the obstacle relative to the probing apparatus may be computed based on the time difference between wave transmission and wave reception. The speed of the obstacle relative to the probing apparatus may be estimated by measuring Doppler frequency shift of the received reflected waves.
However, such an apparatus is structurally complicated with a high implementation cost, and can only detect objects directly exposed in the line of sight. In the case of a freeway environment, the can only detect vehicles directly in front, and can not sense those vehicles further in front spaced by other vehicles.
A communication network based anti-collision system can be further divided into two sub-types. One is an anti-collision system that conducts inter-vehicle communication based on an ad-hoc network. During driving conditions, vehicles in a certain scope communicate information via a temporary network formed by wireless communication. Due to uncertainties in network member and channel access of the ad-hoc network itself, implementing such an application as vehicle collision alert with high real-time requirement on this type of network needs to concurrently implement a perfect communication QoS (Quality of Service) assurance mechanism; thus, its implementation complexity and cost are both very high.
The other is an anti-collision system based on fixedly deployed wireless network infrastructures (e.g., GPRS, 3G, WiFi). This system continuously collects instant vehicle information into a control center, and then distributes or broadcasts relevant information to individual vehicles based on a collective process and analysis of the control center. This type of implementation depends on a perfect infrastructure construction. Further, since communication links are processed by a back-end control central, there is a large delay during the entire transmission. Thus, it is not suitable for applications with very high real-time requirement.
Thus, there is a need for a method that helps avoid vehicle rear-end collisions, which can be easily implemented and can meet real-time requirements.